1. Field of the Invention
The present invention relates to a data input/output apparatus, data input/output method, data recording and reproducing apparatus, and data recording and reproducing method, and more particularly, is suitably applied to a data recording and reproducing apparatus for recording and reproducing video data and audio data.
2. Description of the Related Art
A disk array device provided with a plurality of hard disk drives 2A to 2I as shown in FIG. 1 is available as a data recording and reproducing apparatus.
As this type of disk array device, several types of devices have been proposed depending on the method for distributing input data and parity data for each of the hard disk drives 2A to 2I or the like. However, at present, as shown in FIG. 1, a structure called "RAID-3" is widely used, wherein the input data is stripped (separated) for each bit or each byte in a disk array controller 3 to be read or written all at once by the plurality of hard disk drives 2A to 2H for recording and reproducing data and moreover, parity is generated based on the input data so as to be read and written by the dedicated hard disk drive 2I.
Actually, the disk array device 1 having such the structure has the advantage of being used as a recording and reproducing apparatus which has high reliability for record and reproduction because since the parity data is held in the dedicated hard disk, data distributed to each of the hard disk drives 2A to 2H can be reproduced from the parity data held in the hard disk drive 2I for parity data even when the hard disk drives 2A to 2H for recording and reproducing data break out and moreover, which has a transmission rate which is about N times as fast as an effective transmission rate of one of the hard disk drive 2A to 2H because a plurality of hard disk drive 2A to 2H (for example, N sets) are moved all at once to read and write the input data, and which has a volume which is about N times as large as that of one of the hard disk drive 2A to 2H.
As a consequence, in recent years, the use of the disk array device having such the structure has been proposed as a data recording and reproducing section of a recording and reproducing apparatus for video and audio data which requires a high data transmission rate and a large memory volume.
By the way, in recent years, cable television (CATV) broadcasting stations and general broadcasting stations are gradually demanding to replace a conventional recording and reproducing system for broadcasting programs, which comprises video tape recorders whose set number corresponds to the channel number, with one recording and reproducing apparatus, for coping with the multiplication of channels.
However, the number of channels which is required in this case largely differs depending on the application. Actually, for example, in the use called a broadcasting buffer for temporarily memorizing video and audio data before broadcasting programs, it is sufficient to have only three or four channels output. However, in the use called a near video on demand (NVOD) for broadcasting the same program such as a film or the like by shifting the program by a predetermined time, eight to sixteen channels or more outputs are required.
Consequently, in the case where the recording and reproducing apparatus for broadcasting programs is replaced by one set of recording and reproducing apparatuses, the recording and reproducing apparatus itself is required to be manufactured in a different manner depending on the required number of channels. As a result, since the structure is almost same but the type is different, there is a problem in that no merit is provided in cost, and it will be difficult to cope with the demand for an increased number of channels in the future.